An effective research mentoring relationship is a key element in preparing the next generation of scientists and health professionals to pursue or help make informed decisions about pursuing research careers in science, technology, engineering, mathematics, and medicine (STEMM). Yet, little is known about how specific factors in this relationship affect mentees' academic and career pursuits in research. Empirical evidence indicates that the cultural diversity factors of gender, race, and ethnicity affect undergraduate research mentees' perception of their mentoring experience, however, research on how cultural diversity factors operate in the research mentoring relationship and affect mentees is virtually non-existent. To advance training interventions that build the capacity of research mentors to effectively mentor culturally diverse research mentees, it is necessary to understand the impact of mentor cultural diversity awareness (CDA) on mentee academic and career outcomes. The proposed research addresses this critical need through the following three Specific Aims: Aim #1 will determine how mentors and mentees define mentor CDA and mentors' attitudes about the relevance of cultural diversity (CDR) in research mentoring relationships. Aim #2 will identify relationships between mentor cultural diversity awareness and mentee research-related self-perceptions and positive outcomes (i.e., intent to enter STEMM graduate training or a STEMM career). Aim #3 will investigate, via a randomized controlled trial (RCT), how mentor CDR attitudes affect their response to a training to increase their CDA and whether that training affects 1) mentees' ratings of mentor effectiveness and 2) alignment of mentor-mentee ratings of mentees' research skills/career knowledge. Expected outcomes from this proposal are: 1) a set of indicators and descriptors of mentor cultural diversity awareness (CDA) and a measure of mentor CDR attitudes; 2) validated measures of mentor CDA and CDR attitudes that can be used for mentor self-assessment and to test the effectiveness of CDA training; 3) an intervention to enhance mentor CDA, and; 4) a tested model of research mentoring relationships that includes CDA. This proposal is innovative because it: 1) focuses on cultural diversity factors within research mentoring relationships; 2) is guided by research and theory on career development and cultural competence; 3) employs a mixed-methods approach to develop indicators of and assessment instruments for mentor CDA and mentor CDR attitudes; and 4) analyzes the importance of alignment between mentor-mentee perceptions of critical elements in the research mentoring relationship. The proposed research is significant because it will: 1) shed light on two understudied aspects of research mentoring relationships - the role of CDA and the importance of alignment between mentor and mentee perceptions in the relationship; 2) empirically identify the relevance of mentors' CDA to mentee self-perceptions and positive outcomes; 3) develop and validate measures to assess mentor CDA and CDR attitudes; and 4) produce an RCT-tested intervention to improve mentor CDA.